Method of making and patching furnace walls and linings



Sept. 13, 1932. H. NEUHAUSS METHOD OF MAKING AND PATCHING FURNACE WALLS AND LININGS Filed Sept. 5, 1929 atenized Sept. 13, 1932 NITED STATES HEINRICH NEUHAUSS, OF DU$ST=LBORF, GERMANY METHOD OF MAKING AND ENTERING- .ZUYWNACE WALIS A331) Application filed September 3, 119%. Serial No. 390,083.

My invention relates to methods and ap paratus for forming lining and patching the linings of difierent furnaces.

The main purpose of my invention is to a improve the methods and apparatus for dis tributing a sintering material. upon the interior surface of a furnace which is to be lined, or whose lining is to be patched, or within a form in which a furnace is to be 3% built up of successively sintered layers.

A further purpose is to form a refractory lining within a furnace by the application of a succession of layers of sinterable refractory material and the intervening sucm cessive sintering of these layers in position by an insert within the layers and within which insert the heat is generated inductively by the electric current.

A further purpose is to use an electrically conducting core within a furnace to sinter successive layers of furnace or of lining with in a furnace, building up the lining layer during withdrawals of the sintering core and efiecting the sintering between applications of successive layers.

A further purpose is to prepare a liner for a furnace by sintering a refractory material to form the lining, backing up with pulverulent material and sintering by an inductively heated plug inserted within the hollow of the lining between successive sinterings.

A further purpose is to back a sintered lining by pulverulent material, using for the backing material unsuited for the lining face because not sintered and for the facing material unsuited to support the charge but for the backing and sintering successive layers as required until the lining thickness shall have been secured.

A further purpose is to throw powdered refractory mechanically against previously heated interior side furnace walls so that the powder adheres immediately to the walls, to sinter the refractory in place and without allowing the walls to cool between the operations and to successively apply the refractory and sinter until the desired thickness of the sintered wall has been reached.

A further purpose is to throw refractory powder into a slag side wall furnace after each pouring, while the furnace walls are heated and the refractory will adhere to the walls, sintering separately or by the heat from the next melting operation as desired.

Further purposes will appear in the speci- 5s fication and in the claims.

In the drawing Figures 1 and 2 show the application of the invention diagrammat ically.

In the manufacture of arc furnaces fireno proof linings have been produced by building the furnace from magnesite brick which is heated by short circuit flow of current through electrodes until the brick is at white heat, after which the bottom is sintered from as magnesite powder mixed with open hearth slag, applied by layers.

This method is unsuited. for use for coreless or high frequency furnaces because in these latter furnaces the walls of the furnace 7e crucible or container must be made vertical in order that the induced current can be ap plied to the best advantage.

I have found not only that side walls, including vertical side walls, can be lined to *3'5 advantage by placing a thin layer of sinterable refractory material such as magnesite upon a form in which the ultimate refractory is to be built, or as a liningin a permanent support for furnace use, sintering it by means of graphite or other suitable plug within which an electric current is induced and repeating the operation untilthe furnace wall or lining has been completed, but that the successive layers can be placed conveniently, effectively and uniformly, to good advantage, by a distributing system which throws the refractory against the support or wall to form the layer which is to be sintered.

Even without my distributing and applying method and mechanism, the thin layers of powdered refractory can be placed by the use of a pattern and can be successively sintered after each layer has been laid, but the cooling of the lining between successive applications of the rammed-in layer and sintering causes a good deal of loss of heat and of time before the required lining thickness is secured.

Spraying the refractory against the furnace walls by means of pneumatic spraying apparatus presents another way of applying the lining, but for the fact that the carrier air used for the spraying defeats the purpose of the spraying in that it cools the walls so that the refractory powder will not adhere to them.

To obtain the best results the interior of the form or the refractory wall already applied should be hot when the application is made, in order that the refractory may stick to the wall to the best advantage, and my present application is intended, therefore, to show not only successive application of layers of refractory with successive sintering of the layers, but is intended to show the best form by which this application can be made.

By my invention I coat the interior of the walls mechanically with powdered refractory by throwing the powdered refractory against the heated walls mechanically, and thus secure all the benefits which would accrue from the spraying while avoiding the disadvantages of cooling the walls. As a result I am able to apply a sufiicient thickness of layer for sintering before the walls become too much cooled for the refractory to adhere to them. The subsequent sintering by a graphite plu leaves the walls hot so that advantage can be taken of this sintering heat to insure adherence of the next layer.

Conventional dolomite, magnesite or other refractory furnace linings are shown at 1 and 1 respectively in the two views.

These walls can be heated to a white heat by any convenient means, preferably by the insertion of a graphite plug which is heated inductively by reason of the passage of current through the furnace coil.

After the lining has been heated to a white heat the distributor for the refractory may be inserted. It is supported and handled by an arm 2 and as shown comprises a distributing or throwing disc 3, a shaft 4 by which it is carried, and which rotates in bearings 5 and a charging funnel 6. The upper part of the furnace is protected by cover 7 to prevent cooling of the furnace and loss of the powdered refractory. The shaft is driven in any suitable manner as through a belt 8 connecting the pulley 9 with any driving pulley l0 operated by motor 11. The shaft is supported in bearings 12. A conventional furnace inductor 13 is used by whose current any suitable plug 14 may be heated inductively to react upon the adjoining lining walls. The plug may be made of graphite or other suitable material.

In operation a plug such as 14 of suitable size and shape is inserted and is heated by current induced in it by primary current within the inductor coil.

When the temperature of the wall which is to be covered or lined is sufficiently high the plug is removed and my mechanical distrihutor is applied.

The disc or wheel is rotated rapidly and a refractory is fed to the disc through the charging funnel at the same time that the mechanism is lifted and lowered as required so as to apply the required coating throughout the height of the lining walls. Any refractory which is thrown back by the cover 7. or which fails to stick upon the side wal will drop to the bottom and will help to form the bottom wall, to which refractory can be applied additionally before or after the insertion of the distributor or throwing mechanism.

When a suflicient thickness or powdered refractory has been applied, or when the lining wall has cooled sufficiently so that the refractory no longer adheres properly, the graphite plug can be inserted to sinter the refractory which has adhered and which lies upon the bottom. While the wall is still hot from the sintering operation the plug can be withdrawn and another layer or coating can be applied by the throwing mechanism, the operation being rapid until the lining has been fully formed.

here the lining of a furnace is consumed by the eating away of the slag section my method can be applied to repair the slag lining either by throwing powdered refractory against it, while it is still hot after each pouring to maintain its thickness, or by applying my method of throwing successive layers of refractory against the wall and successfully sintering these layers into complete union to make up any thickness of lining which has been lost. Immediately after a pouring the lining will be hot enough for the powdered refractory to adhere to it and this refractory may be sintered separately or by the next use of the furnace.

In Figure 2 I have intended to illustrate the repairing of the slag stand of the lining though the fi ure is illustrative also of the application of a graphite plug to the sintering of any layer. My throwing mechanism can be used to apply successive layers for any purpose, including the heating of cracks in the lining.

It will be evident that my invention is applicable generally to the formation of a lining by successively applying layers of lining or wall and sintering them and is most desirably carried outby using the heat of one sintering operation to prepare the walls for adhesion of the nextlayer.

It will be further evident that the application of the layers can best be performed by mechanical distribution of refractory dispersed in the act of applying it.

In View of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art,

to obtain all or part of the benefits of my they are hot and shifting the level at which,

invention without copyin the structure the centrifugal discharge takes place so as shown, and I, therefore, claim all such in so to cover the entire extent of the side walls far as they fall within the reasonable, spirit vto be lined.

and scope of my invention.-

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:-

1. The method of forming a refractor for an inductor-coil-surrounded furnace a apted to hold molten metal, which consists in forming the refractory layer by layer of sinterable material and in sintering the layers separately by the heating effect of current induced within the interior of the furnace by current passing through the inductor.

2. The method of sintering a lining within a support to form a crucible adapted to hold molten metal, which consists in laying the refractory upon the side walls of the support layer by layer and successively sintering the refractory layer by layer by the heating effect of current induced Within the interior of the furnace. I

3. The method of sinterin a refractory material within a support to orm a vertical crucible wall adapted to hold molten metal, which consists in inserting the refractory layer by layer, in inserting an electrical conducting body within the refractory after each layer and in sintering the layers by inducing electric current within the insert and removing the insert successively after sintering to. permit the application of the next layer.

4. The method of sintering a refractory upright wall upon a support, which consists in applying the refractory material layer by layer, in interrupting the application of the material to insert a body of electrical conducting material adapted to be heated to high temperature, in inducing electric current within the body to sinter the preceding layer and. in removing the body for the application of the next layer, successively, the heat from each sintering being utilized to assist in adhesion of the next layer.

5. The method of fabricating a lining for an electric furnace which consists in providing'a secondary within the furnace, heating the secondary by induction to heat the wall of the furnace, removin the secondary,

' throwing refractory material against the hot interior wall of the furnace by centrifugal force, replacing the secondary and again heating the secondary to sinter the material thrown and to heat the wall for application of another layer.

6. The methodof making the side walls of electric furnaces, which consists in heating the walls of the electric furnace, in manually feeding finely divided refractory material into the furnaces near the center line of the furnace and centrifugally throwing this material against the side walls while ilii 

